Air Pollutants on the Job May Affect Heart Function

Exposure to occupational and environmental air pollutants can alter heart rates in young, seemingly healthy hearts, researchers report in this month''s Circulation: Journal of the American Heart Association.

These altered heart rates may play a role in the development of cardiovascular disease.

Past studies have linked exposure to air pollution to cardiac death in the elderly. This study is the first to examine exposure to air pollution particles in a younger population.

It is also the first to focus on air pollution in the work environment.

Researchers studied 40 men, average age 38, working as boilermakers in Boston.

Such workers are exposed to many air particles that are similar to those in the general environment, but at a higher concentration.

Researchers measured the workers'' exposure to particulates 2.5 micrograms in diameter or larger (PM 2.5). To determine if these particulate matters were affecting the heart, each worker wore an air sampler and a Holter monitor -- a device that measures heart rate throughout the day -- providing a measurement of heart rate variability.

Heart rates were recorded at five-minute intervals to determine if the heart was beating faster or slower than normal.

Heart rate variability measures cardiac autonomic function, which controls blood vessel size, blood pressure, the heart''s electrical activity and its ability to contract. In this study, heart rate variability was expressed as a reading on a graph, called the five-minute standard deviation of normal RR (SDNN).

The study reported a 2.6 percent decrease in normal heart rate variability in SDNN for every milligram per cubic meter increase of PM 2.5.

The findings of detectable disturbances in autonomic function in this young, otherwise healthy population is of concern, the authors wrote.

Previous studies have shown that heart rate variability is decreased in heart conditions such as coronary artery disease and heart rhythm disturbances, but researchers say further research is needed to understand the significance of these findings.